Structural style of the Chos Malal fold and thrust belt, Neuquén basin, Argentina: Relationship between thick- and thin-skinned tectonics. (December 2015)

• Record Type: Journal Article
• Authors: Sánchez, Natalia; Turienzo, Martín; Lebinson, Fernando; Araujo, Vanesa; Coutand, Isabelle; Dimieri, Luis
• Is Part Of: Journal of South American earth sciences. Volume 64:Part 2(2015:Dec.)
• Page Start: 399
• Page End: 417
• Publication Date: 2015-12
• Subjects: Thick-skinned structures -- Shortening -- Neuquén basin -- Andean tectonics; Geology -- Latin America -- Periodicals; Earth sciences -- Latin America -- Periodicals; Geology -- Antarctica -- Periodicals; Earth sciences -- Antarctica -- Periodicals; Geology -- Caribbean Area -- Periodicals; Earth sciences -- Caribbean Area -- Periodicals; Géologie -- Amérique latine -- Périodiques; Sciences de la terre -- Amérique latine -- Périodiques; Géologie -- Antarctique -- Périodiques; Sciences de la terre -- Antarctique -- Périodiques; Géologie -- Caraïbes (Région) -- Périodiques; Sciences de la terre -- Caraïbes (Région) -- Périodiques; Earth sciences; Geology; Antarctica; Caribbean Area; Latin America; Periodicals; 550.5
• DOI: 10.1016/j.jsames.2015.07.001
• Languages: English
• ISSNs: 0895-9811

Abstract

Abstract: The Chos Malal fold and thrust belt (FTB) is a thick-skinned mountain belt formed by Mesozoic deposits of the Neuquén Basin during the Andean orogeny. Four structural cross-sections in the entire deformed area, supported by field and subsurface data, suggest a strong link between thick and thin-skinned structures. Major Andean thrusts branching from a detachment placed 12 km into the crust created large basement wedges, which were inserted in the cover producing minor order structures. The westernmost of these wedges is exposed forming the Cordillera del Viento, while others basement slices at depth were interpreted from seismic lines. These thick-skinned structures transferred deformation to the cover along the Auquilco Formation and contributed to create all thin-skinned structures surveyed in the Chos Malal FTB. We recognized half-graben geometries in the seismic lines, preserving their extensional configuration, which suggests that the main normal faults were not inverted. Shortenings calculated from the restoration of the four cross-sections are 16.9 km (29.7%), 16.9 km (29.7%), 14.7 km (26.9%) and 14.15 km (26.3%), which evidence a slight diminution of the contraction toward the south probably associated with the plunge of the Cordillera del Viento structure in this segment of the Chos Malal FTB. Highlights: Thick and thin-skinned structures characterize the Chos Malal FTB. Andean thrusts formed basement-involved wedges such as the Cordillera del Viento. First order basement wedges inserted in the cover produced second order folds. Structures in the cover combine fault-bend and fault-propagation folding mechanisms.